THE RED MASON BEE (and relatives).
Bees in general
are very important insects: every third mouthful of our food is dependent
on bees as pollinators of the plants we eat. This is because they
are needed to pollinate flowers. Insects are by far the most important
pollinators. These include moths, butterflies, beetles, flies and
some wasps, but the most important pollinators of all are the bees
: most species of insect-pollinated plants are specialised for pollination
by bees. Bees are the best pollinators because they actively collect
pollen as food for their larvae and they have evolved special structures
on their bodies for handling and transporting pollen. And in the economy
of nature, producing an excess of pollen, together with sweet nectar,
is the price that plants pay in return for the pollination services
provided by the bees.
The Red Mason Bee (Osmia rufa)
The Red Mason Bee is widespread in England and Wales and particularly
likes the range of flowers and trees found in domestic gardens. It
is a more efficient pollinator of fruit crops than the honeybee and
by attracting them to your garden not only will you notice improved
fruit crops - apples, plums, pears, strawberries and raspberries -
but the bees also visit a wide range of garden flowers.
The Red Mason Bee is a solitary bee. That is, each nest tube is the
work of a single female working alone. Unlike the honeybees and bumblebees,
there is no worker caste of sterile females, so she receives no help
from other bees; there is no colony or "hive". The species has an
annual life cycle and they are active from late March to the beginning
of July. Males and females emerge in early spring (late March to April)
and mate. Females then seek out suitable nest sites usually beetle
borings in deadwood, hollow plant stems, or irregular cavities in
stones and old walls. Each nest tube comprises a series of cells.
The female starts her first cell at the back of the nest. She makes
10 to 15 foraging trips to collect sufficient pollen to provision
each cell. The pollen is mixed with a little nectar and this acts
as a food source for the single egg, which she lays immediate-ly before
sealing the cell with a mud partition. The process is repeated until
the tube is filled with a row of about 6 to 10 cells. They also close
the completed nest with mud. This is why they are called "mason" bees.
Females finish nesting in early July. Being a solitary species they
will never live to see their offspring. However in the comfort of
their nests, the eggs hatch into larvae, which feed on the pollen/nectar
mixture. After moulting 4 or 5 times, the full-grown larvae spin a
tough brown silk cocoon and pupate. The new adults form in September
and remain in the cocoon until the following spring when the new generation
of adults emerge and the cycle begins again. Although solitary, mason
bees are attracted to each other. They like to build their nests in
aggregations and females tend to nest close to where they emerge.
The design of the Oxford Bee Company Ltd nest box (see next page)
is such that it will attract a number of nesting females, many of
whose daughters will re-use their natal nests the following season.
Thus a permanent nesting population will be established in your garden.
As with other solitary bees, mason bees are gentle and shy. They do
have a sting but they use it only if they are caught and very roughly
handled. They are docile simply because, unlike the honeybee, they
do not make and store large amounts of honey and therefore do not
have a huge resource to protect.
Research has shown that one female Osmia rufa does the pollination
work of between 120 and 160 honeybees. Osmia species are,
bee-for-bee, much more efficient pollinators of fruit trees than the
honeybee for the following reasons:
1) Osmia can fly in chilly weather and are
often busy pollinating when the honeybee is still in the hive.
2) At any given temperature, Osmia visits
more flowers per minute than honeybees.
3) On any given foraging trip, Osmia is
more promiscuous than the honeybee in terms of the number of trees
visited and hence effects more cross-pollination.
4) Osmia females carry their pollen dry
on a dense brush of hairs under the abdomen and are not very efficient
at grooming themselves. By contrast, the honeybee compacts its pollen
loads on to the hind legs, moistened with nectar and is very good
at grooming itself. Thus, for anatomical and behavioural reasons,
with Osmia there is a greater chance of loose pollen being
transferred from one fruit blossom to another than there is with the
Osmia is almost entirely pollen driven: mason bees do not
store honey and so actively scrabble for pollen at every flower visit,
unlike the honeybee, which is equally interested in collecting large
amounts of nectar and often lands on the sides of fruit flowers to
gain access to nectaries, with minimal contact with pollen-bearing
Native UK Bees Enhance Your Garden but They Need Homes
Besides the honeybee, Britain has more than 250 species of native
bee, many of which help your garden by pollinating flowers. But these
bees are becoming scarce as modern agriculture has produced a landscape
that is rarely bee-friendly these days. With fewer wild flowers and
suitable nest sites, about 25 per cent of our native bees are now
endangered species. In addition traditional apiculture has been badly
hit by the Varroa mite so it is vital to find additional managed pollinators
to complement the honey bee. Importantly, mason bees are not susceptible
to the Varroa mite.
Janet Keene (from information supplied by Chris O'Toole)
Bee Nest Boxes
Sturdy nest boxes can be bought from CJ WildBird Foods . All you need
to do is place them in sunny, sheltered, south-facing position in
the garden and you will attract nest-seeking females of the red mason
bee in early spring. No work is required - if the nest boxes are in
the garden at the right time the bees will find them. Because they
like similar nest sites you could be lucky and also attract the blue
mason bee (Osmia coerulescens) and two species of leaf-cutter bees
(Megachile spp.). The nest tubes mimic the natural nest sites of these
bees: beetle borings in dead wood and hollow plant stems.